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ST LPS33K

A compact barometric pressure sensor. Available in SCK2.2.

Image Credit: STMicroelectronics

Version

This sensor is available on the Urban Board of the SCK2.2. The SCK2.1 and SCK2.3 use the NXP MPL3115A2 instead.

Working principle

The LPS33K is a piezoresistive MEMS absolute pressure sensor. Like the MPL3115A2, it has a thin silicon membrane that bends with the pressure of the air, and piezoresistive elements that change their resistance as it bends. The integrated electronics measure this change, compensate it with an internal temperature sensor, and convert it into a digital pressure value 1.

Usage and considerations

The sensor is on the Urban Board, and its readings are available as:

Metric Shell name Units Enabled by default
Barometric pressure LPS33 Barometric pressure kPa Yes
Internal temperature LPS33 internal temperature ºC No

You can check the readings with the read and monitor commands:

read lps33 barometric pressure

The firmware operates the sensor in one-shot mode: the sensor only takes a measurement when the SCK needs a reading, and stays in power down mode the rest of the time to save power.

Barometric pressure is used in meteorology: decreasing pressure generally indicates bad weather coming, while increasing pressure indicates good weather. It is also used to compensate other sensors that are affected by pressure.

Internal temperature

The internal temperature is the temperature of the sensor itself, which is affected by the heat of the electronics, so it is not a good measurement of the air temperature. For that, use the SHT3X.

Performance

Property Value
Sensor type Piezoresistive MEMS pressure sensor with digital interface (I2C)
Measurement range 30 kPa – 120 kPa (300 – 1200 hPa)

Resources

References

  1. STMicroelectronics. “LPS33K MEMS pressure sensor - Datasheet.” https://www.st.com/en/mems-and-sensors/lps33k.html. ↩